Pre-pregnancy body mass index, maternal weight gain during pregnancy and risk of small-for-gestational age birth: Results from a case–control study in Italy ELENA RICCI 1 , FABIO PARAZZINI 1,2 , FRANCESCA CHIAFFARINO 1 , SONIA CIPRIANI 2 , & GIANPIERO POLVERINO 1 1 I Clinica Ostetrico Ginecologica, IRCCS Fondazione Policlinico Mangiagalli Regina Elena, Universita ` di Milano, Milan, Italy, and 2 Istituto di Ricerche Farmacologiche ‘Mario Negri’, Milan, Italy (Received 26 June 2009; accepted 27 July 2009) Abstract Objective. To analyze the association between body mass index (BMI), gestational weight gain (GWG), and risk of small for gestational age (SGA) birth. Methods. Case–control study: cases included 555 women (mean age 31 years) who delivered SGA babies in two Italian clinics. Controls included women who gave birth at term to healthy infants of normal weight at the hospitals where cases had been identified. Results. Underweight women were at risk of delivering SGA babies (odds ratio, OR, 1.9, 95% confidence interval, CI, 1.6– 2.4) and overweight women had a not significant lower risk (OR 0.7, 95% CI 0.5–1.0). The risk of delivering an SGA baby was higher also for women with less than recommended GWG (OR 1.4, 95% CI 1.1–1.9), whereas gaining more than recommended weight was not significantly protective (OR 0.7, 95% CI 0.5–1.0). The analysis in strata of BMI showed that GWG played a significant role, whereas in strata of GWG pre-pregnancy BMI seemed less important. Conclusion. These results suggest that achieving the adequate weight gain during pregnancy, as recommended by IOM, protects against the risk of delivering an SGA infant also in underweight women. Keywords: Small-for-gestational age birth, gestational weight gain, body mass index, pregnancy, case–control study Introduction Maternal pre-pregnancy weight and gestational weight gain (GWG) have been suggested as factors independently associated with birth weight [1,2]. In particular, the body mass index (BMI) has a documented clinical value, as predictor of obstetric complications as pre-eclampsia, gestational diabetes, fetal macrosomia in overweight women, and small- for-gestational age (SGA) birth and prematurity in underweight mothers [3,4]. The recommendations for weight gain during pregnancy based on pre-pregnancy BMI developed by the Institute of Medicine (IOM) of the U.S. National Academy of Science, aimed to achieve an optimal infant birth weight, 3000–4000 g [1]. Other researches supported the conclusion that pregnant women who gain weight within the IOM recom- mended ranges are more likely to have an infant of optimal size at birth [5–7]. A recent review [8] showed that excessive GWG is more prevalent than inadequate gain and that interventions demonstrate efficacy in decreasing excessive GWG in low-income women. However, most information is gathered from the United States and North Europe (Scandinavia and Denmark). We analyzed the association between BMI, GWG and SGA birth using data from a case–control study conducted in Italy. A specific point of interest is that the study analyses a Southern European population, where BMI and dietary intake are quite different from North American or Northern European Correspondence: Elena Ricci, I Clinica Ostetrica Ginecologica, Universita ` di Milano, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli, Regina Elena, via Commenda 12, 20122 Milano, Italy. Tel: þ39-2-55032318. Fax: þ39-2-50320252. E-mail: elena.ricci@unimi.it; ed.ricci@libero.it The Journal of Maternal-Fetal and Neonatal Medicine, June 2010; 23(6): 501–505 ISSN 1476-7058 print/ISSN 1476-4954 online Ó 2010 Informa UK Ltd. DOI: 10.3109/14767050903216025 J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by 79.45.164.192 on 05/14/10 For personal use only.